Apparatus for Embedding Tissue Samples

ABSTRACT

A histology tissue embedding apparatus including a reservoir for an-embedding medium and an outlet valve connected to the reservoir through which the embedding medium is dispensable, and including trigger means which control the operation of the outlet valve, the trigger means having a rest position in which the outlet valve is closed, wherein the rest position of the trigger means in relation to the outlet valve is adjustable.

The present invention relates to an apparatus for embedding tissuesamples, typically for histological or histopathological examination.

When tissue samples are collected, it is common to fix the samples formore convenient analysis e.g. viewing under a microscope. One method offixing is by freezing using a cryostat. An alternative is to treat thetissue samples with various fluids and then to embed each sample in ablock of paraffin wax. The embedding process includes several steps,such as heating the paraffin wax, placing it and the tissue sample in asuitable container and setting the wax. Laboratory equipment known as an“embedding centre” is typically used to carry out these processes andthe present invention is primarily concerned with providing an embeddingcentre incorporating one or more improvements.

A tissue embedding centre will generally include a reservoir for themolten paraffin wax and a nozzle connected to the reservoir throughwhich the molten wax can be dispensed into a mould. It is known toinclude a trigger in the form of a paddle adjacent to the nozzle forcontrol of the wax through the nozzle. Typically, the paddle will belocated behind the nozzle (i.e. on the opposite side to the equipmentoperator) and pressure on the paddle to push it away from the nozzlewill operate the nozzle so as to dispense the wax. The paddle is biasedto return to a rest position i.e. if there is no operator pressure on itthen it returns to the rest position, in which the nozzle is controlledto be closed.

Different equipment operators will use the paddle in different ways e.g.some will operate it by pressing on it with the tissue cassette andothers by pressing on it with one of their hands. This can mean that theembedding centre equipment is easier to use for some operators thanothers. Generally, one aim of the present invention is to provide anadjustable paddle i.e. a paddle (or other wax dispenser controlmechanism) whose rest position relative to the nozzle (or other waxdispensing outlet) is adjustable.

Accordingly, in a first aspect, the present invention provides ahistology tissue embedding apparatus including a reservoir for anembedding medium and an outlet valve connected to the reservoir throughwhich the embedding medium is dispensable, and including trigger meanswhich control the operation of the outlet valve, the trigger meanshaving a rest position in which the outlet valve is closed, wherein therest position of the trigger means in relation to the outlet valve isadjustable. In this way, the position of the trigger means can be variedto suit different operators of the equipment.

Preferably the embedding apparatus will include heating means which areusable to heat the reservoir so as to maintain the embedding medium(e.g. paraffin wax) in a molten, liquid, state and the reservoir will beheated so as to be usable. Preferably the outlet valve is a nozzle,which may be oriented substantially vertically so as to dispense theembedding medium into a mould held beneath the nozzle.

Preferably the trigger means is a paddle, which may be locatedsubstantially behind the nozzle (from the equipment operator'sperspective) as described above. Preferably the rest position of thetrigger means is adjustable in a direction away from the outlet valvee.g. so as to create more space between the trigger and the outletvalve.

In some embodiments, a portion of the trigger means is slidably attachedto a body of the embedding apparatus. Preferably, the trigger means alsoincludes a locking means (e.g. a locking screw) to retain it so that itis not slidable under normal user operation of the trigger when thelocking means is locked, but when the locking means is unlocked thetrigger is slidable so as to adjust its position.

One further problem with some existing tissue embedding machines is thatthe working areas may be poorly illuminated, or the illumination lampsprovided may be such that they get in the way of the equipment operator.

Accordingly, in a further aspect, the present invention provides ahistology tissue embedding apparatus including an equipment housinghaving an outlet valve for dispensing a tissue embedding medium into atissue mould and a working area below the nozzle in which the operatorholds a tissue mould in use, wherein the working area also includes aseparate cold area which is coolable using cooling means to atemperature suitable for setting embedding medium, wherein the equipmenthousing incorporates one or more LED lights to illuminate both theworking area and the cold area. The use of dedicated LED lights in thisway provides both a better quality of lighting and also a less intrusivelighting apparatus.

In use, once a tissue mould has been filled with the embedding medium(which will typically be paraffin wax and which will be referred to assuch from now on although other embedding media are also intended to beincluded), typically some of the wax will be in unwanted areas e.g.overflowing the tissue cassette and/or mould and stuck to its sides.

Accordingly, in a further aspect, a histology tissue embedding apparatusof the present invention includes trimming means for trimming theembedding medium from a cassette. Preferably, the trimming meansincorporates a trimming surface, which includes a plurality ofcorrugations which, when a cassette is rubbed across the surface by auser, help to remove excess embedding medium. Preferably the corrugatedsurface is heated so as to further facilitate the removal of the excessembedding medium.

In some embodiments of the invention, the trimming means is incorporatedinto a working surface of a part of the equipment, such that thetrimming surface is substantially flush with the surrounding workingsurface. This means that when not in use the trimming means does noteffectively interfere with the user's operation of the equipment and canfunction as a normal part of the working surface.

Periodically, it is desirable to drain the paraffin wax from knownembedding equipment. Generally, this can be a tricky and messy task. Theapplicant's own prior art embedding equipment is provided with a draintube through which the paraffin wax may be drained into a suitablereceptacle. However, such drain tubes have a tendency to get clogged-up.

Therefore, in a further aspect, the present invention provides ahistology tissue embedding apparatus which incorporates a removableembedding medium waste receptacle which, in use, collects excessembedding medium from e.g. the working surface of the equipment duringthe normal embedding process. In addition, the apparatus may be providedwith drainage means via which embedding medium is drainable from thereservoir. The outlet of the drainage means is preferably directed intothe location of this receptacle. However, to facilitate the collectionof a large quantity of waste, embodiments of the invention may furtherbe provided with an interchangeable, larger, waste receptacle which isattachable to the apparatus in place of the normal waste receptacle.This simple and convenient system allows the embedding medium to bedrained without the need for separate reservoir drainage tubes etc as inthe prior art equipment. It also preferably conveniently overhangs thebench in front of the instrument.

In a yet further aspect, the present invention provides a histologytissue embedding apparatus incorporating document holding means, whichare usable to hold documents required by the equipment operator.Preferably the document holding means are movable from an open positionin which they are available to hold a document as described, and aclosed position in which they are less obtrusive to the operator of theequipment than when in the open position.

Embodiments of the invention may incorporate any one or some or all ofthe above aspects, together with any one or some or all of the featuresdescribed below.

Embodiments of the present invention will now be described withreference to the accompanying drawings in which:

FIG. 1 is a perspective view of a histology tissue embedding centreincorporating aspects of the present invention.

FIG. 2 shows the apparatus of FIG. 1 further including a cold moduleaccording to aspects of the present invention.

FIGS. 3-5 show variations on the apparatus of FIGS. 1 and 2 toillustrate how the apparatus may be used in practice.

FIG. 6 shows a tissue cassette and mould for use with the presentinvention.

FIG. 7 shows the operation of an embodiment of the tissue embeddingmedium dispenser according to the present invention.

FIG. 8 is a cross-sectional view through a part of an embodiment of thepresent invention to illustrate the tissue embedding medium dispenser.

FIGS. 9 and 10 illustrate embodiments of the invention incorporating anembedding medium drainage module.

FIG. 11 shows the operation of the embedding medium drainage module ofFIG. 10.

FIGS. 12-14 show views of a further embodiment of a document holder inaccordance with aspects of the present invention, in this examplemounted on a cold module.

FIG. 1 shows a histology tissue embedding system incorporating aspectsof the present invention. The system consists generally of a heatedmodule (shown in FIG. 1) and a cold module (shown attached to the heatedModule in FIG. 2).

The function of the heated module is primarily to dispense a tissueembedding medium (in this case paraffin wax, but other suitable mediamay be used) into tissue moulds and to provide storage for the variousitems used. The primary function of the cold module is to cool thetissue moulds after dispensing so that the wax sets.

The tissue embedding apparatus shown in FIG. 1 includes a tank 1 for thewax. The tank 1 is heated by suitable heating means (not shown) in orderto raise the temperature of the wax so that it is in liquid form fordispensing. Wax is added to the tank via lid 1 a. The apparatus includesa base mould storage compartment 2 for storing the base moulds intowhich wax will be poured, and a tissue storage tank 3 for storing tissuesamples in the respective cassettes. There is also a cassette lidstorage dish 4 located adjacent the tissue storage tank 3.

In use, liquid wax is dispensed from the wax tank 1 via an outlet valve,which includes nozzle 9 a. The rate of dispensing of the nozzle iscontrolled by a wax dispense flow control 9 and the operation of thenozzle is controlled by a trigger means, which in this example is adispense lever 8. When the dispense lever 8 is in its rest position, thenozzle is closed and no wax is dispensed. However, when the wax dispenselever is pressed by the operator away from the nozzle 9 a (i.e. towardsthe tank 1), the nozzle is opened and wax is dispensed in accordancewith the setting of the wax dispense flow control 9.

In use, a base mould will be held underneath the nozzle 9 a, on top of ahot spot plate 6. The hot spot plate is heated by further heating means(not shown) which helps to prevent the wax from solidifying too quicklyonce it has been dispensed into the base mould.

Adjacent the hot spot plate 6 is a cold spot plate 7, which is cooled bycooling means (not shown). After wax has been dispensed into the basemould, the base mould may be placed by the operator on cold spot plate 7to increase the rate of solidification of the wax. Once the wax hassubstantially solidified, excess wax may be removed by the operatorusing wax trimmer 11.

The general working area of the equipment, for use by the operator, isenclosed by dashed line 12 i.e. incorporates the wax trimmer 11, the hotspot plate 6, the cold spot plate 7, and other areas for the placementof cassettes etc. In addition, there is a forceps block 10 for storageof the operator's forceps.

Waste wax accidentally dropped onto the working area 12, and otherareas, is collected via a series of grooves and channels in the workingarea (one example is identified with numeral 13) and is collected in awaste wax tray 5 which will be described in more detail later.

FIG. 2 shows the apparatus of FIG. 1 with the addition of a cold module,identified generally with reference numeral 20. The cold moduleincorporates a large cold plate 21, which is useable to cool a number ofbase moulds. In addition the cold module incorporates a storage drawer22 for further equipment storage.

An additional feature of some embodiments of the invention is documentholding means, which in this embodiment is provided by an openable tray23. The tray 23 is movable between a closed position (shown) in which itis substantially flush with the surrounding surface of the equipment, soas to be unobtrusive, and an open position in which it is usable to holda document for the operator. A further embodiment of a document holderwill be described later.

More and more use of printed lists of notes and information aboutspecimens is being provided to assist the embedding process.Traditionally, these notes were placed near to the embedding centre oron any convenient surface that they could rest on. However, thesepositions were not typically in the correct place to allow the user toreadily see the notes. The incorporation of a document holder into theembedding centre (in this example mounted on the cold stage module)allows the user to view and if necessary mark up the notes with minimuminterruption to the embedding process.

The apparatus is controlled by a control system (not shown) and theuser-operable functions are accessed by means of a touch screen 14.

In use, the apparatus according to the present inventions may beoperated in various ways, depending on user preference. FIGS. 3 to 5show three different options. In FIG. 3, moulds and cassettes will betaken from the centrally located storage areas, processed by fillingwith wax on the left of the equipment, and then moved to the right-mostend for the cold storage module. An alternative is shown in FIG. 4,where the cold storage module is located on the left hand side of theparaffin wax dispensing part of the apparatus. A further option is shownin FIG. 5, where the apparatus includes an additional cold storagemodule, for further capacity.

As mentioned previously, the embedding process typically causes someexcess wax to be left on the outer face of the cassette and/or mouldwhich needs to be removed so it can be clamped firmly during thesubsequent sectioning process. Traditionally this is done manually usinga thin blade to scrape excess wax from the cassette faces.

The wax trimmer device improves this process. A series of grooves (e.g.square but could be other shapes such as triangular, saw tooth etc) arein a metal plate that is heated to about the wax melting temperature.The face of the cassette can then be rubbed across these grooves whichcauses the wax to be removed. The device is incorporated into theembedding module so that cassettes can be fully prepared and finished onthe one instrument rather than having to trim at a later stage in theprocess. An additional benefit is that the wax trimmer forms part of theembedding deck and is preferably flush with it, and it can continue tobe used for normal embedding activities, thus keeping space to aminimum.

FIGS. 6 to 8 illustrate generally the filling of a mould with wax. FIG.6 shows a base mould 30 into which some wax 32 is placed. The tissuespecimen 34 is placed on top of the lower layer of wax 32 and the basemould is moved on to the cold spot plate, typically until the waxbecomes translucent. Following that, the tissue cassette 36 is placedinto the base mould 30, on top of the sample 34 and the cassette isfilled with wax via the nozzle 9 a as shown in FIG. 7.

As previously described, the operation of nozzle 9 a is controlled viadispense lever 8. FIG. 8 shows a cross-sectional view through theportion of equipment including the wax tank and nozzle dispensingsystem.

Users will actuate the lever 8 by a variety of means e.g. finger,forceps, embedding mould. They may also be working with different sizecassettes and moulds. Adjustment of the distance from the lever to thenozzle allows the user to set the distance optimally to suit theirneeds.

Traditionally, the lever position is fixed relative to the nozzle.

A knob 38 behind the lever is used to release it, which is then adjustedbefore locking in position. The lever assembly 39 is mounted on aslideway 37 to allow the adjustment. Different locking methods could beused and/or with one or more pre-defined positions.

Tissue samples can be quite small, and orientation of the sample canalso be important. The placement process is manually carried out by anoperator using forceps so good illumination of the working area isimportant. Traditionally there was some basic illumination mounted nextto the dispense nozzle and then supplementary illumination provided by alight on a flexible arm that could be directed as required by the user.However, this extra light could also get in the way of the operator asthe embedding process is a very manual process.

The invention provides for one or more (in this case 3) of highintensity LED lights, 40, 41, 42, mounted in front of and to the sidesof the dispense nozzle. They are preferably angled to provide a fullarea of illumination both under the nozzle and spreading out over thewider working area. In addition one or more (2 in this case) LED lights,43, 44 are mounted further back on the instrument structure to providemore general illumination of the working area.

This combination of lights provides good illumination over the fullworking area without any obstructions to the user, or the need fordifferent users to adjust the position of the flexible light for theirown individual preference.

FIGS. 9 to 11 show the aspects of the present invention relating todrainage of the embedding medium from the equipment.

Molten wax is a difficult substance to work with and dispose of. Once itis removed from the heated storage area it can start to solidify on thesurface and can block drain pipes, tubes or other devices. It can alsobe difficult to drain into waste bags.

The embedding centre has a small wax waste drawer 5 that collects excesswax during the normal embedding process. To fully drain the wax, thewaste drawer 5 is removed and replaced with an enlarged container 50that hangs over the front of the bench. Preferably, this containermounts in the same guides as the wax waste drawer. Once drained, thewaste container can be easily removed and the wax disposed of.

FIG. 11 shows drainage nozzle 52 used to drain the wax 54 from thetank/reservoir 1.

FIGS. 12-14 show a further example of a document holder in accordancewith aspects of the present invention. In this example, the documentholder (indicated generally by reference numeral 60) is shown attachedto a cold module 20. However, the document holder 60 may equally beattached to a hot module, or indeed any other part of an embeddingcentre.

The document holder 60 includes a document support 62 on which, in use,a document will be placed. The document holder 60 also includesattachment means, identified generally by the numeral 64. In thisexample, the attachment means 64 include a plate 66 which restsgenerally on top of a part of the cold module 20, and (68), (70) whichhelp to secure the document holder to the cold module. Other attachmentmeans may of course be used.

One of the preferred features of a document holder according to thepresent invention is that while fixed in place on a part of theembedding centre, the orientation of the document support 62 may beadjusted with respect to the embedding centre. In this example, theattachment means are such that the document tray 62 may preferably betilted forwards and backwards i.e. in the direction of the arrow A shownin FIG. 13. Additionally or alternatively, the attachment means are suchthat the document tray 62 may be adjusted from side to side i.e. in thedirection of the arrow B shown in FIG. 14. The side to side adjustmentis such that the document faces in a direction towards an operatorlocated not directly in front of the part of the embedding centre onwhich the document holder is mounted, for example in the direction ofarrow C shown in FIG. 14. In the particular example shown in FIG. 14,this is achieved by an adjustable side member 72, which increases thespacing of one side of the document tray 62 from the part of theembedding centre on which it is mounted. Other means to achieve the sameresult may of course be used.

When used in this specification and claims, the terms “comprises” and“comprising” and variations thereof mean that the specified features,steps or integers are included. The terms are not to be interpreted toexclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or in the followingclaims, or in the accompanying drawings, expressed in their specificforms or in terms of a means for performing the disclosed function, or amethod or process for obtaining the disclosed results, as appropriate,may, separately, or in any combination of such features, be utilised forrealising the invention in diverse forms thereof.

1. A histology tissue embedding apparatus incorporating a documentholder, which is usable to hold documents required by the equipmentoperator.
 2. An apparatus according to claim 1 wherein the documentholder is movable from an open position in which it is available to holda document and a closed position in which it is less obtrusive to theoperator of the equipment than when in the open position.